The present invention is directed to a cutting insert and, more particularly, to a titanium carbonitride-based cermet cutting insert (hereinafter referred to as "TiCN"), which exhibits superior wear resistance and toughness. Such a cutting insert is capable of a long service life and is resistant to damage such as chipping and breaking of the cutting edge while in continuous and discontinuous use.
In recent years, a demand for factory automation has created a need for longer lasting cutting inserts which are tough and wear resistant.
In an attempt to fulfill this demand for superior cutting inserts, Japanese Laid Open Patent Publication No. 50-86512, in conjunction with various technical reports, discloses a TiCN-based cermet which consists essentially of 5 to 30 vol % of a metallic binding phase, which is mainly composed of Co and Ni, together with two hard dispersion phases. One of the two hard dispersion phases has a single-phase structure while the other hard dispersion phase includes a single-phase structure formed of a composite carbonitride solid solution.
The carbonitride solid solution contains Ti and at least one of Ta, Nb, V, Zr, W, Mo and Cr (hereinafter referred to as ("Ti,M)CN").
However, the abovementioned prior art cutting inserts made of TiCN-based cermets have been unable to fulfill the abovementioned demand because of their inability to withstand the demands of continuously cutting steel in an industrial setting. Notwithstanding the toughness of these prior art cutting inserts, such cutting inserts are prone to extensive breakage and chipping of their cutting edges while in continuous use.